Mycobacteria, particularly M. avium and M. tuberculosis, are a major cause of morbidity and mortality in AIDS. Because infection with these pathogens occurs mainly in tissues, bacilli may only intermittently be present in the circulation or in Other clinical specimens. The lack of a simple quantitative test which can be performed on easily-obtained specimens has hampered evaluation Of new regimens for prevention and treatment of mycobacterial disease, as well as delaying diagnosis and treatment. The stated intent of PA-96-068 is to encourage creative preclinical research emphasizing under-exploited facets of the basic biology, biochemistry, and pathophysiology of AIDS-related opportunistic infections, leading, in part, to development, preclinical validation, and standardization of rapid, non-invasive detection methods for early and specific diagnosis and for evaluation of responses to therapy. In response, this application will seek to determine the degree to which species-specific secreted mycobacterial antigens appear in the urine of infected hosts, and further, to determine whether detection of these products can be developed into sensitive, specific, and rapid tests for diagnosis and monitoring of treatment of mycobacterial disease. The specific aims of this proposal are: 1) The identification and characterization by 1- and 2-D SDS-PAGE, western blot, and N-terminal amino acid sequence analysis, of species-specific antigens and/or epitopes in experimental and human M. avium and M. tuberculosis infection; and 2) Development, evaluation, and validation of quantitative assays for these antigens. Particular attention will be given to detection of two proteins in urine, as preliminary studies suggest that these antigens are abundantly produced, have species specific epitopes, and can be detected more readily in urine as compared to serum. This project may ultimately lead to the development of a novel assay which can be used clinically for diagnosis and management of latent and active mycobacterial infection in AIDS.